Computer for aviation trainers and the like



y 8,1952 H. F. SCHAEFER, JR 2,602,244

COMPUTER FOR AVIATION TRAINERS AND THE LIKE Filed March 27, 1947 12 Sheets-Sheet l uunmmm.

H. FREDERICK SCHAEFER, JR.

IN V EN TOR.

ATTORNEY July 8, 1952 H. F. SCHAEFER, JR

COMPUTER FOR AVIATION TRAINERS AND THE LIKE Filed March 27, 1947 12 Sheets-Sheet 2 MANIFOLD PRESSURE L E V E L m 5 T A mm M M U R \l O E T F 5 H WO I5 T UW NE LE PMW MW T L A mwzsnwmmuz FULL THROTTLE LINES suowme ALTITUDE EFFECT PRESSU UN HORSEPOWER +MANIFOLD CONSTANT RF! M. SEA LEVEL LlNES K sc g gggggm w/f FiG.2

ATTOR N EY y 8, 1952 H. F..SCHAEFER, JR 2,602,244

COMPUTER FOR AVIATION TRAINERS AND THE LIKE Filed March 27, 1947 12 Sheegs-S heet s H. FREDERICK SCHAEFER,JR

INVENTOR.

A'r'ronne y 1952 H. F. SCHAEFER, JR 2,602,244

I COMPUTER FOR AVIATION TRAINERS AND THE LIKE Filed March 27, 1947 12 Sheets-Sheet 4 EVEL- FULL THROTTLE H DRSEPOWER H.FREDERICK SCHAEFER JR.

. INVENTOR.

ATTORNEYS y 8, 1952 H. F. SCHAEFER, JR 2,602,244

COMPUTER FOR AVIATION TRAINERS AND THE LIKE 12 Sheets-Sheet 5 Filed March 27, 1947 H. FREDERICK SCHAEFER JR mmvroli 8Y4 Z g {'2' 5 n'rogmsv y 1952 H. F. SCHAEFER, JR 2,602,244

COMPUTER FOR AVIATION TRAINERS AND THE LIKE 12' Sheets-Sheet 6 Filed March 27, 1947 H .FREDERICK SCHAEFER,JR.

INVENTOR.

W/{MWL ATT ORNEY July 8, 1952 H. F. SCHAEFER, JR

COMPUTER FOR AVIATION TRAINERS AND THE LIKE Filed March 27, 1947 '12 Sheet s-Sheet 7 ATTORNEY July 8, 1952 Filed March 27, 1947 ALRSPEED 8 6 FIG.

FIG.I6

FIG. 6

H. F. SCHAEFE/R, JR

COMPUTER FOR AVIATION TRAINERS AND THE LIKE 12 Sheets-Sheet s FIG.4

BRAKE HORSEPDWER FIG. 9

FIG.8

' FIG.I2

H FREDERlC-K SCHfiEFERAR ATTORNEY July 8, 1952 H. F. SCHAEFER, JR

COMPUTER FOR AVIATION TRAINERS AND THE LIKE Filed March 27, 1947 12 Sheets-Sheet 9 LEVEL SmSSm a MASTER PIVOT FIG IO H F RE D ERICK SCHAEFERJ.

mwsmozm BY g /f 34 ATTORNEY y 1952 H. F. SCHAEFER, JR 2,602,244

COMPUTER FOR AVIATION TRAINERS AND THE LIKE Filed March 27, 1947 12 Sheets-Sheet l0 ATTORNEY FIG. l4

y 8, 1952 H. F. SCHAEFER, JR 2,602,244

COMPUTER FOR AVIATION TRAINERS AND THE LIKE Filed March 27, 1947 12 Sheets-Sheet 11 RIGHT TURN 4 LEFT TURN 4 RATE OFTURN N -N bm H. FREDERICK SCHAEFERJR.

INVENTOR.

ATTORNEY y 8, 1952 H. F. SCHAEFER, JR 2,602,244

COMPUTER FOR AVIATION TRAINERS AND THE LIKE Filed March 27, 1947 12 Sheets-Sheet 12 m 654 650 \J' FIG. I5 6 Z 664 H. FREDERICK SCHAFEFERAR.

INVENTOR.

W/KM' ATTORNEY Patented July 8, 1952 UNITED STATES- PATENT OFFICE COMPUTER FOR AVIATION TRAINERS AND THE LIKE Hans Frederick Schaefer, Jr., Marblehead, Mass, asslgnor to Link Aviation, Inc., Binghamton, N.'Y., a corporation of New York Application March 27, 1947, Serial No. 737,696

. g V 4 Claims. (01.35 12) My invention relates to grounded equipment for teaching the art of piloting aircraft. Such equipment has been in widespread use for several years, the best known type of such equipment being disclosed in United States Patents 1,825,464 and 2,099,857 issued to Edwin A. Link, Jr. My invention will be described in conjunction with trainers of the type illustrated in the two'mentioned United States patents, but upon a reading of the disclosure of my invention it will be readily realized that my invention is equally useful in other types of aviation trainers including trainers of the type havinga stationary fuselage.

Grounded aviation trainers in general include a cockpit having a seat for the student pilot, and inside the cockpit are positioned movable rudder pedals and a movable stick or'aileron and elevator control, simulating the corresponding flight controls of a real plane. Simulated rudder, elevator and aileron trim tab controls-may also be provided. Also, there are provided a simulated throttle lever control, a simulated propeller governor (engine speed) control and a simulated flaps lever. An instrument panel is mounted ahead of the students seat, and upon this'panel are mounted a full complement of instruments simulating the instruments of a real plane. Such instruments include an air speed indicator, altimeter, vertical speed indicator, tachometer, manifold pressure gauge, flaps position indicator, artificial horizon, directional gyro, magnetic compass, radio compass, etc. i

Interposed between the manual controls (throttle lever, engine speed lever, flaps lever, rudder pedals, aileron and elevator control) and the instruments on the instrument panel are various selected types of computing mechanisms the purpose of which is to cause the instruments on the instrument panel to register indications at all times dependent upon the combined settings and combined effects of the settings of the various manual controls corresponding to the instrument indications of a real plane of the type being simulated when the manual controls of the'plane are set and retained in positions corresponding to the positions of the controls in the trainer.

My invention relates to a completely diiferent and novel form of computing arrangement for interposition between the manual controls and instruments, so that the instruments register correct indications according to the various positions of the manual controls, and so that fuselage movements, when my invention is used in conjunction with a movable fuselage, properly respond to the settings of the manual controls. There are known to the prior art electronic computers, mechanical-electric computers, and

pneumatic computers. My invention relates to a pressure and engine power output. The. exact position of the pivot in the surface is transferred;

through any suitable means to additional apparatus which is responsive to the exactposition of the pivot in the surface. c

As will become clear upon a reading of this disclosure, the geometrical surface through which the pivot is moved is preferably a plane, and the position of the pivot in the surface is'transferred through mechanical connecting means to other mechanical members which are positioned in accordance with the position of the pivot.

However, the geometrical surface may, for example, be conical or spherical in shape, and the means operated by the moving pivot may be other than mechanical.

The correct positioning of the floating pivot may be achieved by the preparation of a graph,

plotting lines for at least two selected" input variables, and then plotting lines representing the output'variable or variables relative to the first plotted input variable lines. Mechanism is then designed which will properly position the pivot along the lines of the graphaccording to the value input variables, sothat the pivot is prop-.- erly positioned relative to the lines of the output variable or variables for the values of the instant input variables. The output mechanism is connected to the pivot to be positioned by-the pivot according to the position of the pivot relative to the output variable line or lines, and the position of this output mechanism may be taken as the true measure of the instant output varia' ble or variables.

This disclosure will show three diiierent embodiments of my invention, the first being an engine computer which has three variable inputs of throttle lever setting, engine speed lever setting and altitude, and the two outputs of manifold pressure and horsepower available. The second computer is the flight computer, which has the two variable inputs of attitude and air speed and the two variable outputs of vertical speed and horsepower required. The third computer is the air speed-engine power turn computer, and has the two variable inputs of.

power.

Fig. 3 shows the same information as Fig. 2,

replotted in a form adaptable to the design of a suitable computing apparatus, and including a schematic showing of a portion of the engine computer.

Fig. 4 is a perspective view of the engine computer.

Fig. 5. shows the same information as Fig. 3,

together with a schematic showing of certain parts of the engine computer.

Fig. 6 is a perspective view of a portion of the prior art trainers.

Fig. '7 is a view of a portion of the eng ne computer, and more particularly the portion thereof operated in response to changes in assumed altitude.

Fig. 8 is a general perspective view of the flight computer and associated apparatus.

Fig. 9 is a graph showing the effect of power and attitude on air speed and vertical speed.

Fig. 10 is a view showing the information contained in Fig. 9 replotted in a form suitable for the design of a computer, as well a schematically showing certain of the parts of the flight com-.- puter..

Fig.'11' is a view of the spring connecting as,-

sembly shown in Fig. 8.

Fig. 12 shows the altitude computing apparatus and other associated parts.

Fig. 13 is a graph showing the effects of air speed and throttle setting upon rate of turn Fig. 14 shows the information given by Fig. 13

replotted in a form lending itself to the design of a suitable computing apparatus, as Well as scher.

matically showing certain parts of the rate of turn computer.

Fig. 15. shows the rate of turn computer as well as certainlparts of the prior art trainers associated therewith.

, Fig. 16 is a schematic drawing showing the relative positions in which the drawings of this application may be placed in order to show the apparatus of this invention in one view.

Of the foregoing, Figures 3, 5, l and 14 show the exact relative positions of the pivots and the lengthsof the links of the embodiment of each of the computers disclosed herein.

Reference is now made to Fig. 1 which is a general disclosure of grounded aviation trainers of the type covered by U. S. Patents 1,825,462 and 2,099,857. Such trainers comprise a stationary base It above which is mounted a fuselage I2 simulating the fuselage of an actual aircraft. Within this fuselage there is a seat for a student positioned to, the rear of the control wheel 30. The fuselage I2 rests upon a universal joint I4 and this joint is supported by the main central vertical spindle I which is rotatably held by the stationary base Ill. The conventional octagon is desigspeed (R. P. M.) and altitude on the dependent variables of manifold pressure and brake horsenated by I5. and as is well known to the prior art, octagon It is affixed to the main spindle I5 below the universal joint It by means of suitable horizontal arms (not shown) so that the octagon I5 rotates with the spindle I5 and fuselage I2 relative to the stationary base It.

A forward pitching bellows I1 and a rearward pitching bellows I8 are provided, the bottom portions of each of these bellows being affixed to the arms which ho d the octagon I6 relative to the vertical spindle I5, and the upper ends of these bellows are aifixed to the bottom I2a of the fuselage 12. These two bellows lie in a vertical plane through the longitudinal center of the fuselage Upon the admission of vacuum to the forward bellows I1 and atmosphere to the rear bellows 58, the former bellows collapses and the latter expands causing the nose of fuselage I2 to be lowered. On the other hand, the admission of vacuum to the rear bellows I8 and of atmosphere to the fore bellows I'I causes the nose of fuselage I2 to rise. As is well understood, the admission of vacuum and atmosphere into the bellows I! and I8 may be controlled by the student in the trainer by moving the control wheel 39 fore and aft of the fuselage I2, so that the student may control the diving and climbing position of the fuselage I2. The diving and climbing position of the fuselage are sometimes referred to as pitching.

At the same time trainers of this type have a left banking bellows I9 as Well as a right banking bellows 2fl'upon the opposite side of the universal joint I4 from the bellows I9. The admission of vacuum and air into these bellows may be controlled by the student through a rotation of the control wheel 33 so that he may place the fuselage I2 in any desired banking position within the. limits of the apparatus.

Trainers of the type being considered are often equipped with a stick instead of a control wheel, and it will be readily apparent to those skilled in the-art, after reading this application, that they can substitute a stick for the wheel 39.

Fixedly carried by the octagon Iii are the horizontal arms 2i which support the turning motor 22. By means of a well known pulley arrangement connecting the turning motor 22 with the stationary. base Ifi,'the student in the'fuselage I2 may, by pressing either of the rudder pedals 676 or 671, energize the turning motor 22 in such a direction that the turning motor 22, supporting arms 2I, octagonIS, bellows I'i, I8, I9 and 2d, spindle I5, universal joint I4 andfuselage I2 will rotate either to the left or right, as desired, relative to the stationary base I 6. Thus the student may control the simulated heading of the fuselage I2 in the same manner that he would control the heading of a plane in actual flight.

The steps 25 and 26 and door 26a allow access to the interior of the fuselage i2 and a slidable canopy 21. may be used to completely encompass the cockpit of the fuselage I2 in order to simulate blind flying conditions. The canopy 21 may be made of a suitable translucent material in order to permit enough light to enter the cockpit of the fuselage to enable the student to manipulate the trainer without the assisance of artificial lights placed in the interior of the fuselage. Such conditions closely simulate day-time blind flight conditions. On the other hand when it is desired to simulate night-time blind flying conditions, a suitable opaque material such as a cover may be placed over the canopy 27 in order that no light enters the cockpit through this canopy. The student must then rely upon theconventional artifi-L Engine computer Reference is. now made to Fig. 2 which is a brake horsepower-manifold pressure graph showing the effects of independent variables of throttle lever setting and engine speed (R. P. M.) and altitude on the dependent variables of manifold pressure and brake horsepower. On this graph are four constant R. P. M. lines-4600 R. P. 1800 R. P. M., 2000 R. .P. M. and 2200 R. P. M. These lines assume altitude to be zero, and are labelled Constant R. P. M.--sea level lines. Drawn across these lines are three throttle position lines, viz.. full throttle, throttle and /2 throttle, each of these three lines being so labelled. The following typical information may be secured from this graph:

FULL THRQTTLE 1600 R. P. M. produces 33" manifold pressure and 337 brake horsepower 1800 R. P. M. produces 34%". manifold pressure and 410 brake horsepower 2000 R. P. M. produces 35.8" manifold pressure and 465 brake horsepower 2200 R. P. M. produces 37 manifold pressure and 525 brake horsepower THREE-QUARTERS THROTTLE 1600 R. P. M. produces 30" manifold pressure and 295 brake 1800 R. P. M. produces 28.8" manifold pressure and 320 brake 2000 R. P. M. produces i 28.5" manifold pressure and 340 brake horsepower 2200 R. P. M. produces 27 manifold pressure and 350 brake ONE-HALF THROTTLE 1600 R. P. M. produces 1 V 27 manifold pressure and 2:)5 brake 1800 R. P. M. produces 25" manifold pressure and 263 brake 2000 R. P. M. produces 24" manifold pressure and 268 brake 2200 R. P. M. produces 23 manifold pressure and 270 brake Therefore this graph clearly shows the various manifold pressures and brake horsepowers produced at sea level altitude by various combinations of throttle setting and engine speed. Such a graph may be produced by any suitably trained engineer for any selected engine. I

Also shown on the same graph are dotted lines showing the effect of altitude upon horsepower and manifold pressure as developed by a full throttle setting at selected engine speeds. For example, at full throttle, 5000 feet, 1600 R. P. M., there is produced 27 /2 inches of manifold pressure and 280 horsepower. At full throttle, 20,000 feet, 1600 R. P. M., there is produced inches of manifold pressure and 165 horsepower.

Having graphed'the independent variables of throttle setting, engine speed, and altitude, against the dependent variables of manifold pressure and brake horsepower, the next step is the provision of a computing mechanism including three separate inputs corresponding to the three independent variables and two separate outputs corresponding to the two dependent variables. Any linkage that canmove a master pivot in two dimensions through a plane surfacemay be used. 'Qne suchv form of linkage will now be disclosed.

horsepower horsepower horsepower horsepower horsepower horsepower horsepower Reference is made to Fig. 3 where four links are shown pivoted together to form a rhombus.

The rhombus includes the fixed master pivot FMP, the manifold pressure arm MPA, the horsepower arm I-IPA, the auxiliary links I00 and I02,

and the altitude master pivot AMP. The manifold pressure arm MPA has its lower end pivoted I06, and the right end of the horsepower arm ispivoted at the fixed master pivot FMP.

Assuming that it is desired to position the manifold pressure arm MPA about the fixed master pivot FMP in accordance with the factor of assumed manifold pressure, the manifold pressure arm MPA may be swung about pivot FMP so that pivot I04 at the upper end of arm MPA describes the manifold pressure are I08. This are may then be divided into increments of any suitable amount-in the illustrated case, the increments being five inches of manifold pressure.

By placing pivot I04 about the five inch mark on the manifold pressure are and swinging the altitude master pivot AMP through its limit of travel, the five inch manifoldpressure are at the left of Fig. 3 will be described. The pivot I04 may successively be placed on the 10, 15, 20, 25, 30, 35 and 40 inch points on they manifold pressure are I08, and corresponding arcs drawn generally parallel to the five inch manifold pressure are, by swinging the altitude master pivot AMP.

Assuming that it is desired to position the horsepower arm HPA about the fixed master pivot FMP in accordance with the factor of assumed horsepower, the horsepower arm HPA may be swung about pivot FMP so that pivot I06 at the left end of arm HPA describes the horsepower are III This are may then be divided into increments of any suitable amount-in the illustrated case the increments being one hundred horsepower. j

Then, by placing pivot I06 above the zero,'100, 200, 300, 400 and 500 marks on the horsepower arc H0, the horsepower arcs in the, upper left of Fig. 3 may be described byswinging the altitude master pivot AMP, these ares being generally at right angles to the manifold pressure arcs.

Thereafter, the position of the horsepower arm HPA about the fixed master pivot FMP depends upon the position of the altitude master pivot AMP relative to the horsepower lines of Figs. 3. For example, when the altitude master pivot AMP is at any point along the 300 horsepower arc, pivot I06 will be above the 300 point on the horsepower are III], and the horsepower arm HHA will be in the angular position about the fixed master pivot FMP which is selected for an assumed engine power output of 300 horsepower. .Similarly, the position of manifold pressure arm MPA about the fixed master pivot FMP depends upon the position of the altitude master pivot relative to the manifold pressure lines of Fig. 3.

For a disclosure of the actual physical construction of the rhombus structure disclosed in Fig. 3, reference is made to Fig. 4. where the fixed master pivot FMP, the manifold pressure arm MPA, the pivot I04, link I00, the altitude m'aster'pivot AMP, the link I02, pivot I00 and the horsepower arm HPA are shown. The fixed master pivot FMP takes the form of a stud II2 fixed to .the post M4, the flange H6 of which is afi'ixed .by screws [I8 to the plate I39, which in turn is affixed to the floor I2a, of the fuselage I2., Gear IIS is affixed to spacer H20. which in turn is affixed to arm NIPA so that gear IIS rotates-with the manifold pressure arm MPA about the fixed master pivot FMP. The altitude master pivot AMP includes the stud I22.

Inasmuch as the position of the altitude master pivot AMP determines the positions of the manifold pressure arm MPA and the horsepower armHPA, it is necessary that the altitude master pivot AMP be positioned relative to the manifold pressure and horsepower lines on the graph in accordance withthe three independent variables of throttle setting, engine speed and altitude. By properly positioning the altitude master pivot relative to the manifold pressure and "horsepower lines in accordance with the assumed conditions of throttle setting, engine speed and altitude,the angular positions of the horsepower arm EPA and manifold pressure arm MP-A become a correct measure of the instant assumed dependent variables of horsepower and manifold pressure.

Reference is now made to Fig. where the manifold pressure and horsepower arcs previously described in conjunction with Fig. 3 are shown. In addition to the manifold pressure and horsepower arcs, there are also shown in Fig. 5 four sea-level constant engine speed arcs, viz., 1600 R. P. M., 1800 R. P. M., 2000 R. P. 1M and 2200 R. P. M. Also, the full throttle line, the throttle line and the /2 throttle line are shown. By comparison of Fig. 5 with Fig. 2, it will be seen that the four sea level constant speed engine lines and the throttle lines in Fig. 5 generally cross the manifold pressure and horsepower arcsat the same values as in Fig. 2. For exam:- ple, in both Figs. 2 and 5, at sea level, full throttle and 1800 R. P. M., on both graphs there is developed very close to 35 inches of manifold pressure and 410 horsepower. In both Figs. 2 and 5 at sea level, throttle and 2000 R. P. M., there is produced a manifold pressureof 24 inches and a horsepower of about 270 is developed. .Each of the R. P. M. arcs is an arc of a circle having its center along the arc I53, the 2200 R. P. M. are being centered at the 2200 point on are I53, etc.

Considering first the independent variables of assumed engine speed and assumed throttle lever setting, if the altitude master pivot AMP is positioned along the proper R. P. M. line of Fig. 5 in accordance with the assumed engine speed, or intermediate the R. P. M. lines for intermediate settings, and then the altitude master pivot AMP is positioned along, the full throttle line when the throttle lever in the trainer is in the full throttle position, or along the three-quarter throttle line when the throttle lever is in the three-quarter throttle position, or along the onehalf throttle line when the throttle lever is in the one-half throttle position, or in any other proper position relative to the three just mentioned lines according to in-between settings of the throttle lever, it will be appreciated that the altitude master pivot will be positioned in such position that the angular position of the manifold pressure arm MFA- about the fixed master pivot FMP will be a proper measure of the assumed manifold pressure for the existent throttle lever setting and assumed engine speed, and the altitude master pivot AMP will be positioned so that the angular position of the horsepower arm HPA positions of the manifold pressure arm MPA and horsepower arm HPA about the fixed master pivot FMP will be a true measure of the assumed manifold pressure and assumed horsepower output, and the assumed manifold pressure and assumed horsepower output will be dependent upon the factors of assumed throttle lever setting, assumedengine speedand assumed altitude.

First, means will be described for positioning the. altitude master pivotAMP in accordance with the factors of assumed engine speed and assumed throttle lever setting, and then means will be disclosed for modifying the position of the altitude master pivot in accordance with the assumed altitude.

I Reierenceiis now made to Fig. 6 where a lever I20 is shown, this lever being pivoted upon stud I22 which is suitably fixed within the trainer fuselage I2 as seen inFig. 1. This lever represents the engine speed lever or propeller governor control lever of a plane equipped with a constant speed propeller. The settingof the lever, in the case of a real plane, determines the speed at which the engine of the plane runsthe farther ahead the lever is set, the higher the speed at which'the engine will run.

The friction disc I24 is fixed upon stud I22 to bear against lever I20 to retain that lever in any position in which it is placed by the student within fuselage I2.

Pivot-ally attached to the lower end of the engine speed lever I20 is the forward end of link I26, the rear end of which is pivotally attached to the upper end of arm I28 which is pivoted upon the fixed stud I 29.

The forward. end of link I30 is pivotally attached to the arm I28 at I3I, and the rear end of link I30, as seen in Fig. 4, is pivotally attached to the outer end of arm I32 which is affixed upon the upper end of shaft I34 by means of set screw I35. Shaft 13:4 is rotatably mounted in the bear- I ing housing I38 which is suitably afiixedto the plate I by screws I32. Arm N52 is aifixed upon the lower end of shaft I34 by means of set screw I as, and the lower end of link I46 is pivotally attached to the outer end of arm I42. The upper end of'link S lt is pivotally attached to arm I48, the right end of which ispivotally mounted upon the fixed stud I50 which is carried by fixed plate I39 and spaced therefrom by spacer I41. Carried by the left end of arm I48 is the stud I54 which pivotally carries the upper end of link I55, the lower end'of which is pivoted upon the stud I58, the vertical axis of which forms the sea level master pivot SLlVIZP.

Considering now Figs. l and 6, it will be understood that when the engine speed lever I20 is moved ahead by the student to produce a higher assumed engine speed, the link I26 and upper end of arm I28 move to the rear. The link I30 also moves to the rear, and by parts I32, I34 and I42, the link I moves downwardly in Fig. 4, pivoting arm I48 counterclockwise about the ,fixed pivot I50. Accordingly, the pivot I54 moves counter- 9 clockwise about pivot I50, and the sea level master pivot SLMP in Fig. 4 is moved downwardly.

When the engine speed leverI20 of Fig. 6 is moved to the rear to produce a lower assumed engine speed, it will be appreciated that the just described parts will be moved in the opposite directions from those just specified,

Reference is now made to Fig. 5, whereinthe arm I48, pivot..l50', pivot I54, arm I56 and sea level master pivot SLMP are also schematically shown, Bearing in mind the immediately preceding description of the actual structure as disclosed in Figs. 4 and 6, it will be appreciated that the position of the engine speed lever I20 determines the position of arm I48 about the fixed pivot I50, and consequently determines the p'osi-- tion of the pivot I54 along the arc I53. position of pivot I54 in turn determines above which of the constant R. P. M. lines the sea level master pivot SLMP is positioned.

Accordingly, when the engine speed lever- I is positioned in the 1600 R. P. M. position, the described arrangement places pivot I54 in the 1600 R. P. M. position above are I53, and the sea level master pivot SLMP will be placed above the 1600 are. Similarly, when the engine speed lever I20 is in the 1800, 2000, 220-0 or any intermediate position, pivot I54 is properly positioned along arc I53, and the sea level master pivot SLMP is properly above the 1800, 2000 or 2200 arc, or properly in an intermediate position, as the case may be. Means will now be disclosed forproperly positioning the sea level master pivot SLMP along the selected R. P. M. arc in accordance with the instant position of the simulated throttle lever.

Reference is again made to Fig. 6 where the simulated throttle lever in fuselage I2 is designated by I60. This lever is pivotally mounted upon fixed stud I22, and integral therewith is the arm I62, to the rear end of which is affixed the upper end of link I64. The lower end of link I64 is pivotally attached to one arm of bell crank I65 which is pivoted upon stud I66, and the forward end of link I90 ispivotally attached to the other arm of bell crank I65.

In Fig. 4 it will be seen that the rear end of link I90 is pivotally attached to the outer end of arm I92, the other end of which is afiixed upon the upper end of shaft I06 by means of set screw I94. The lower end of shaft I96 is rotatably mounted in bracket I01 which is affixed to the fixed plate I39 by means of screws I08. A gear sector 200 is provided, and it has an integral boss 202 which is affixed upon shaft I96 by screw 204. The teeth 206 of sector 200 mesh with gear 208 to drive the same, gear 208 being affixed upon shaft 2I0 which has its lower end rotatably held by hearing 2I2 which is aflixed to plate I39 by screws 2I4. Affixed upon the upper end of shaft 2I0 is the inner end of arm 2 I6, to the outer end of which is pivotally attached one end of arm 2I8, stud 220 pivotally connecting the arms 2I6 and 2I8. The other end of arm 2I8 connects with stud I58, the vertical axis of which positions the sea level master pivot SLMP.

Considering Figs. 4, 5 and 6, when the throttle lever I60 is moved ahead to simulate the opening of the throttle in a real plane, arm I62 and link I64 move upwardly, rotating bell crank I65 counterclockwise and moving link I90 to the rear. The rearward movement of link I90 results in a counterclockwise rotation of army I92, shaft I96 and sector 200, as seen from above, and in a clockwise rotation of gear 208, shaft 2 I0 and arm 2I6, also as seen from above. The rotation of.

The

arm 2I6 will result in an upward movement of link 2I8, and the sea level master pivot SLMP will be moved clockwise in an arc about pivot I54; because link I56 prevents the sea level master pivot SLMP from moving in any other path. It will be recalled that the location of pivot I54 is deter,- mined by thev setting of the engine speed lever I20 so that the sea level master pivot SLMP is at all times properly placed above one of the engine speed lines of Fig. 6, or intermediate the engine speed lines, according to the instant assumed engine speed.

It will be appreciated that when the throttle lever I60 is moved to the rear, to simulate the closing of the throttle in a real plane, the sea level master pivot SLMP will be rotated counterclockwise in Figs. 5 and 6 about the pivot I54.

Briefly, therefore, the setting of the engine speed lever determines the position of pivot I54, and accordingly, along or near which of the R. P. M. lines in Fig. 6 the sea level master pivot SLMP shall move. Then, the position of the throttle lever determines at which point lengthwise of the selected R.'P. M. line, or lengthwise near the selected R. P. M. line, the sea level master pivot SLMP shall be positioned. As previously stated, when the engine speed lever is in the 1600, 1800, 2000, or 2200 position, or at some intermediate value, the sea level master pivot will be properly positioned with respect to the R. P. M. lines. Also, when the throttle lever is in the full throttle position, the pivot 228 is positioned as shown in Fig. 5 so that the master sea level pivot SLlVIIP must be positioned along the full throttle line of Fig. 5. When the throttle lever is in the threequarter position, pivot 220 will be at the point %T in Fig. 5 so that the sea level master pivot will be along the three-quarters throttle line of Fig. 6, and when the throttle lever is in the one-half position, the pivot 220 will be at the point indicated in Fig. 5 by /2T, so that the sea level master pivot SLMP will be along the one-half throttle line. For points other than the full, three-quarters and one-half setting of the throttle lever, the pivot 220 will be properly positioned to place the sea level master pivot SLMP relative to the three basic throttle lines of Fig. 5.

Accordingly, the disclosed structure provides means for placing the sea level master pivot in the proper position relative to the manifold pressure and horsepower arcs in Fig. 5 to indicate the manifold pressure and horepower that is theoretically being produced in accordance with the instant combined positions of the engine speed lever and throttle control. The two factors of engine speed and throttle setting determine the factors of manifold pressure and horsepower when altitude is zero. Accordingly, the sea level master pivot is always positioned in accordance with the factor of sea level manifold pressure.

Means for causing the altitude master pivot AMP to follow the sea level master pivot SLlVH? exactly when altitude is assumed to be Zero, and means for properly displacing the altitude master pivot AMP from the sea level master pivot SLMP according to the factor of assumed altitude will now be disclosed, so that the altitude master pivot AMP is properly positioned at all times in accordance with the three independent variables of throttle lever setting, engine speed lever setting, and assumed altitude. Then, as previously made clear, the manifold pressure arm MPA and horsepower arm EPA will be properly positioned about the fixed master pivot FM? for the instant assumed manifold pressureand horsepower. I l 3 V Reference isnow made to Figs. 4 and '7 where the sea level master pivot SLMP is shown. The resultant position of this pivot determines the position of one end of arm 2355' which is pivoted about-the stud222 carried by arm 234which in turn is pivoted about'the axisof stud 235' carried by member 238 which is affixed to plate 139 by screws 240. The axis of stud 235' forms the anchor pivot AP. Integral withthe arm 230. is the shorter arm 230a, and pivotally attached to the outer end of arm-230a, by means of stud242, is one end of link 2'44, the other end. of which is pivoted to:stud 245 carried by block 225 which slides upon rod 250. One end of rod 250 is carried by block i2 5 which, as previously described, is carried by stud I22 which forms the altitude master pivot AMP.

Stud 2435 also carries spacer 252, and above this spacer is pivotally connected one end of link 254, the other end of which is pivotally connected to stud 255 carried by one end of arm 2.53 which is integral with sector 255a. Sector 258a carries a stud Ziiilto which is anchored one end of spring 262, the other end of which is anchored to arm 234a integral with arm 234. The crank formed by-arm 258 and sector 258a is pivoted upon stud 254 carried by arm 232. A stud 255 is carried by the lower side of sector 25841 to engage the arm 234 under predetermined conditions to be later described.

Cable 268 has oneend connected to sector 258a, and this cable travels on pulley 2'10 which is rotatably mounted upon the upper end of member 212', by means of stud 214, member 212 being afiixed to plate I39 by means of screws 210.

For present purposes it is sufiicient to explain that the cable 258 is moved by an altitude unit to be later described so as to always be positioned in accordance with the instant assumed altitude of the trainer. As assumed altitude is increased, the unit to be described releases cable 258 by an amount linearly proportional to the change in assumed altitude, and spring 262 keeps cable 255 tight and at the same time rotates sector 258a and arm 258 counterclockwise as seen from above through an angle dependent upon the change in assumed altitude. On the other hand, when assumed altitude is decreased, the altitude unit pulls cable 258 to the right linearly proportional to the decrease in assumed altitude, and sector 258" and arm 258 are rotated clockwise about pivot 264 through a proportionate angle.

The distance from the sea level master pivot SLMP to the pivot 232, the distance from the altitude master pivot AMP to the pivot 232, and the distance from the anchor pivot AP to the pivot 232 are all equal. Therefore, the altitude master pivot AMP must at all tim be directly over the sea level master pivot SLMP or at some point on an are passing through the sea level master pivot SLMP and the anchor pivot AP, which are has its center at the common pivot 232. The anchor pivot AP is positioned at the zero horsepower-zero manifold pressure point, as clearly shown in Fig. 5. By displacing the altitude master pivot AMP from the sea level master pivot SLMP toward the anchor pivot AP by an amount equal to the loss of manifold pressure and horsepower for the assumed altitude, the altitude master pivot AMP will be properly positioned in accordance with the three input variables of throttle setting, engine speed and altitude, and the manifold pressure arm MPA and horsepower arm "EPA will be properly angularly positioned about the fixed master pivot FMP according to instant assumed manifold pressure and assumed. horsepower available. For example, when the sea level master pivot'SLMP is positioned at the 2200 R. P- M., full throttle position, and assumed altitude is zero, by position-. ing the altitude master pivot AMP over the sea level master pivot SLMP, both .the sea level master pivot and the altitude master pivot will be in the 37 inches manifold pressure and 515 horsepower position. The manifold pressure harm MPA and horsepower. armIIPA will be properly positioned.

Under the same circumstances, except altitude assumed to be 5,000 feet, by reference to Fig. 2 it willbe seenthat ahorsepower of 440 and a manifold pressure of 30.6 inches is produced. This point is, plotted on Fig.5 and labelled 5000. Corresponding valuesfor altitudes of 10,000 feet, 15,000 feet and 20,000 feet are ascertained by inspection of Fig. 2, and the corresponding points in Fig. 5 are labelled 10,000, 15,000 and 20,000. It is apparent that thereafter if when assumed altitude is 5000 feet and the throttle is in the full position and the engin speed lever is set for 220.0 R. P. M., the altitude master pivot AMP is positioned above the point 5000 in Fig. 5, the manifold pressure arm MPA and horsepower arm EPA will be properly positioned to account for the loss of manifold pressure and horsepower occasioned by assumed altitude. Corresponding positioning of the-altitude master pivot AMP for altitudes of"10,000, 15,000 an'd'20,- 000 feet wf l produce similar results.

The'displacement of the altitude master pivot from the sea level master pivot along an are between thesea level master pivot and the anchor pivot according to the instant assumed altitude by an amount depending upon the decrease of manifold pressure andhorsepower as a result of the factorof assumed altitude isaccomplished by the apparatus disclosed in Fig; 7 which was laid out as follows: i

The common pivot 232 was selected. and the lengths of arms 230, 250 and 234 made equal, these lengths being of the required lengthto 1ocatethe pivot 232 at the center of the are passing through the anchor pivot, the sea level-full throttle position of the sea level master pivot, and the requiredpositions of the altitude master pivot When'altitude is 5,000 feet, 10,000 feet, 15,000 feet and 20,000 feet, the throttle lever is in the full position and the engine speed lever is set for 2200 R. P. M. The are in question is designated AMP/ arc in Fig. 5.

The sea level master pivot was positioned along the AMP arc in four different positions, and the corresponding positions of arm 230 were designated I, II, III and IV. At the same time the corresponding positions of pivot 242 were designoted I, II, III and IV The required position for arm 250 corresponding to each of the four basic positions of arm 230 to halve the angular distance between the sea level-master pivot SLMP and the anchor pivotAP were then found and marked I II III IV 5 s *2" an r and the required position for arm 250 corresponding to each of the four basic positions of arm 230 to quarter the angular distance between the sea level master pivot SLMP and the anchor fraction 13 pivot AP were also found, and these positions were designated v r L i Land The altitude master pivot AMP was placed over the sea level masterpivotSLMP, or in the assumed zero altitude position, and the length of links 244 and 254 were selected so pivot 256 overlies pivot 232 and so that link 254'lies parallel to rod 250. The -altitude masterpivot AMPis then the sea level master pivot SLMP .and'stop 266 engages the top of arm 234. I

With a compass set to the length of link244, arcs were successively struck from the points I, II, III and IV. The arc-drawn from the point I passes through or very near to the points I I, '4 and 2 the are drawn from the point II passes through the points I 1 H, and g, etc.

Accordingly, the numerator of each fraction denotes the basic position of the sea level master pivot ,SLMP along the AMP arc, and the denominatorlof each'fraction denotes the proportion of the angular distance from. the sea level master pivot SLNLP to the anchor pivot AP in which the altitude master pivot AMP is to be placed for the two selected altitudes when altitude is decreased by one-quarter and one-half. For example, the

indicates the position of the pivot 246 when arm 230 is in the 'III position and the altitude master pivot AMP is to be one-quarter of the angular distance from the sea level master pivot SLMP to the anchor pivot AP. The linkage is shown in this position in Fig.7.

Next, with a compass set to the length of link 254, the point was found from which an arc with thisradius could be struck through the above mentioned intersections labelled with fractions of the same denominator, or as close thereto as possible. The points are designated 2 and 4. Pivot 262 was then located at the center of an arc through stud 232, point 1 and 2.

In View of the above construction, it willbe appreciated that the sea level master pivot SLMP positions the arm 230 on one of the points I, II, III, or IV (to take the arbitrarily selected points only), and arm 230a positions pivot 242 at the corresponding point I, II, III or IV. The pivot 256 will be over pivot 232 when assumed altitude is zero. Accordingly, the pivot 246 will be above a line through pivot 232 and the sea level master pivot SLMIP, and the altitude master pivot AMP will be over the sea level master pivot SLMP. The manifold pressure arm MPA and horsepower arm HPA will be positioned in the sea level manifold pressure and horsepower positions.

The apparatus is then arranged so that when the sea level master pivot SLMP is positioned in the full throttle 2200 R. P. M. position, with a sea level manifold pressure of 3'7 inches and a horse power of 515, and assumed altitude is 9000 feet, the pivot 232 is over the point 4, and the altitude master pivot AMP will be displaced one-quarter of the distance from the sea level master pivot to the anchor pivot AP, or in the 26.5 inches of manifold pressure and 390 horsepower position.

7 stant assumed altitude.

By reference to Fig. 2 it will be noted that under the same assumed conditions a manifold pres-' sure of 26.5 and a horsepower of 385 is'produced.

Also, under the same assumed conditions, ex-

basic illustrated points of sea level, nine thou- I sand feet and twenty thousand feet, and any position of the sea level master pivot SLMP intermediate the I,'II, III and IVpositions or along any of the R. P. lines other than thef2200 R. P. M. line, the apparatus shown in Fig.7 will properly displace the altitude master pivot AMP an angular distance alongthearc between the sea level master pivot SLMP and the anchor pivot AP dependent upon-the position of cable 258. Inasmuch a cable 268' is always positioned in accordance with theinstant altitude, so will be pivot 256, and by means of links 244""and 254 the pivot 246 and altitude master'pivot will bedi'splaced from the seat level master pivot SLMP by an angular distance dependent upon the in- V The altitude master pivot AMP will be positioned close to theproper position relative to the manifold pressure and horsepower arcs.

Accordingly, the altitude master pivot always positions the horsepower arm HPA and'manifold pressure arm MPA about'the fixed fmaStr pivot FMP in accordance with the factors'of instant assumed manifold pressure and instant assumed horsepower output. These two factors are properly dependent upon the factors of throttle lever setting, engine speed and altitude.

In Fig. 4, the gear H8 is fixed to the spacer I luawhich in turn is fixed to the manifold pressure arm MPA to rotate aboutthe fixed master pivot FMP with arm MPA, and this gear drives gear 210 which is fixed upon the input shaft 212 of the manifold pressure selsyn motor transmitter designated generally by 215. The housing of this transmitter is numbered 216 and is carried by clamp 218 which in turn is supported by bracket 280 which'ig afiixed to' plate I39 by screws 2'52. The selsyn transmitter 214 is connected by electrical cable 284 with the manifold pressure selsyn receiver 286 which forms a part of the manifold pressure indicator designated generally by 288, and which is mounted upon the instrument panel 29 in fuselage l2, a 'shown in Fig. 1. The manifold pressure indicator 288 includes a dial 290 calibrated like the manifold pressure indicator'in a real plane, and upon the output shaft 252 of selsyn receiver 286 is mounted needle 29 which moves over dial 290 to: indicate to the student in'fuselage I2 the instant assumed manifold pressure. I r

The disclosed arrangement ofselsyn transmitter and receiveris well known to the art, and need not be further explained. It will be readily realized by those skilled in the art that the just disclosed arrangement will cause the needle 294 to be positioned relative to dialv 290 in accordance with the position of the'manifold pressure arm MPA about the fixed master pivot FMP. Accordingly, the manifold pressure indicator alwaysinr dicates to the student in the trainer the instant tion thereof.

assumed manifold. pressure, computed as previously described by the. engine computer disclosed in Fig. 4.

Itxwill be appreciated by'those skilled in the art that an instrument simulating the tachometer of a real plane may be regulated by the setting of the engine speed lever to indicate to the student the instant assumed engine speed. Such aninstrument may be mounted upon the instrument panel 29 of Fig. 1.

Referring again to Fig. 4, the link 333 has its lower end pivotally connected to the horsepower arm EPA as shown, and therefore the position of this link is a measure of the instant assumed horsepower. Pivotally attached to the upper end of link 300 is the arm 362 which forms the input of the conventional follow-up motor or power amplifying assembly shown in box form and designated generally by 304. The output of this follow-up assembly is in the form of arm 3% affixed upon output shaft 384. Inasmuch as such motor follow-up assemblies are widely used in p the art, it is unnecessary to explain the construc- It is sufi'icient to merely state that the follow-up assembly always moves arm 3% through an angle equal to any angular movement of input arm-332, and in the same direction as any movement of arm 302.

Pivotally attached to arm 385 is the forward end of link 308, which as seen in Fig. 8 has its other end pivotally attached to the left end of walking beam 310 which is pivoted about stud 3|2 which, for present purposes, may be considered station ary. The forward end of link 314 is pivoted to walking beam 310, and the rear end of this link is pivotally attached to the outer end of arm.

316, which together with shaft 3l3 and arm 328 form a bell-crank. Shaft 3|8 may be suitably supported by a bracket (not shown). fixed to any convenient fixed part inside fuselage 12. The right end of link 3221s pivotally attached to the outer. end of arm 320, and the other end of this link is pivotally attached to the forward end of the horsepower walking beam 324 which is pivoted upon stud326 held by yoke 328. The rear end of walking beam 324 is pivoted upon stud 366.

In view of the disclosed connection between the horsepower arm HPA and the horsepower walking beam 324, it will beappreciated that the forward end of the horsepower walking beam is always positioned in accordance with the instant assumed horsepower available as calculated by the engine computer of Fig. 1. An increase in horsepower available moves the left end of walking beam 324 and pivot 326 to the left, while a decrease in horsepower available moves the left end of the horsepower walking beam and pivot 328 in the opposite direction. The purpose of this positioning of the horsepower walking beam and pivot 326 will be later described.

Flight computer Reference is made to Fig. 9 which is a graph showing the effect of horsepower available and plane attitude on airspeed and vertical speed for a selected type of airplane. The factors of horsepower available and plane attitude are the independent variables, and these two variables determine the dependent variables of air speed and vertical speed. For example, in level flight seventy-five horsepower will produce an airspeed of 114 miles per hour with a positive vertical speed. of 500 feet per minute; a nosing up of the plane of' two degrees and 200 horsepower will produce a. zero vertical speed and an air speed of miles per hour. An attitude of six degrees climb and 350 horsepower will produce a positive. vertical speed of about 750 feet per minute and an airspeed of about 128 miles per hour.

In Fig.9, if any two of the variables are known, the other tWom-ay be ascertained by inspection. For instance, if it is known thatthe airplane is flying at miles per hour and descending 500' feet per minute, the airplane must be nosed down close to 3 degrees and is flying with225. horsepower. Accordingly, this graph shows the horsepowerrequired to maintainwany selected set of flight conditions.

Reference is now made to Fig. 10 where the information shown in the graph of Fig. 9 is replotted in a form which lends itself to the design of a satisfactory computer. By comparison of the graphs of Figs. 9 and 10, it will be seen that the air speed lines, horsepower required lines, attitude lines and vertical speed lines of both graphs bear the same relative positions and values.

The linkage schematically shown in Fig. 10 and actually shown in Fig. 8, to both of which reference is made, followsmuch the same pattern as that previously disclosed in connection with the engine computer. A fixed master pivot FMPZ is provided, this pivot being the stud 340 integral with the member 342 which is anixed to plate 344 bymeans of screws 346. Pivoted upon the fixed master pivot FMPZ is one end of the arm 348, the other end of which is pivotallyconnected by stud 350 to the upper end of link 352.

The lower end of link 352 is pivoted upon stud 354, the vertical axis of which forms the master pivot MP. Also pivoted upon stud 354 is the right end of link 3543, the left end of which is pivoted upon stud 358, and the lower end 'of arm 360 is also pivoted upon this stud. The upper end of arm 360 is pivoted upon stud 340 which is the fixed master pivot FMPZ.

Arm 360a is integral with arm 36D, and the outer end of arm 360a carries stud 382 to which is pivotally connected the left end of arm 364, the other end of which is pivoted to stud 366 carried by the right end of the horsepower walking beam 324.

The stud 354 which forms the master pivot MP also carries block 368 which is slidably mounted upon rod 31! carried by bushing 313 which is rotatably. mounted upon stud 312 which in turn is held by bearing 314 which is afiixed by screws 316 to plate 344. p

Also carried by stud 354 which forms the master pivot MP is the lower end of link 31!], the upper end of which is pivotally connected by stud 312 to arm 314 which with arm 316 forms a bell crank pivoted upon stud 318 integral with bracket 386 which is affixed to plate 344*by means of screws-382.

The flight computer of Fig. 8 was determined as schematically shown in Fig. 10. A radius equal to the desired length of arm 314 was selected, and the altitude arc in the upper right of Fig. 15 was drawn. This arc was divided in increments of changes of four degrees of fuselage attitude, viz., 12, 8, 1, level, +4, +8 and +12. A radius equal to the desired length of link 3'llljwas selected, and from each of the selected points on the attitude are an arc was drawn. These arcs were labelled +12, +8, +4, 0, +4, +8 and +12. The outer end ofthis last radius coincides with the master pivot MP, and consequently, when the fuselage is in the -4 degree attitude, the master 

